The present invention relates to a shift controller in a wide sense for switching two-wheel drive/four-wheel drive of a motor vehicle or for switching a transmission channel of the drive force as in a transmission, and particularly to a shift controller to be operated by an electric actuator. Further, it can be utilized also for a motor drive type control module similar to the former. Moreover, this is related also to a rotating position detection sensor used for such a switching device as described.
In conventional devices, a shift controller described in U.S. Pat. No. 6,155,126 has a gear arranged capable of transmitting torque between a motor and a shift rail as an output member, and comprises a housing for receiving a motor and a gear mechanism, and a cover, wherein a control circuit board including a microcomputer is mounted on the inner surface of the cover, and the control circuit board is formed with a plurality of rotation detectors and its processing circuit.
Further, there has been known, as described in Japanese Patent Laid-Open No. 94512/1999, an angle sensor in which a magnet is mounted on a rotational body, and a change in magnetic field of a magnet depending on the position of the rotation angle is measured by a magnetic sensor element, the sensor comprising a measuring element for determining a direction signal depending on the direction of magnetic field crossing the measuring element, and an evaluation circuit for determining an angle position from an output signal of the magnetic sensor element and an output signal of the direction measuring element.
Further, there has been known a method for computing an angle using a threshold calculated by a pre-stored reference table and calibration as described in SAE2001-01-0984 as a processing technique of a rotating position signal.
The aforementioned conventional techniques pose a problem that since the control circuit board is exposed into the gear receiving chamber, the control circuit is erroneously operated due to dust, oil and iron powder generated in the gear receiving chamber.
The aforementioned conventional techniques pose a problem that since the rotational body and the rotation angle sensor or the signal processing circuit of the sensor are exposed to the gear receiving chamber, the rotation angle sensor or the signal processing circuit is erroneously operated due to dust, oil and iron powder generated in the rotational body.
In the aforementioned conventional techniques, to detect a rotation angle over 360 degrees of an output rotating shaft, a first sensor mechanism for detecting a rotational direction and a rotation angle of a motor, and a second sensor mechanism for detecting an angle position of the output rotating shaft are necessary, and the sensor mechanisms were complicated. Further, there poses a problem that the resolution of the senor is affected by a gear ratio.
The aforementioned conventional techniques pose a problem that since a sensor output signal is a pulse, only the dispersal angle detection can be done.
The aforementioned conventional techniques pose a problem that since a Hole element is used, it is necessary to keep the distance between a rotational body and a sensor element within 3 mm, thus posing a problem that management of distance between the hole element and the rotational body is severe.
In the aforementioned conventional techniques, a magnet is mounted directly on a rotational body, and to excite an angle sensor, it is necessary to increase the magnetic force of a magnet or to make the distance between the magnet and the sensor narrow, thus posing a problem with cost of the magnet and assembling property.
In the aforementioned conventional techniques, to secure the transmission mechanism, it is necessary to apply counterbore milling processing to the cover on which a gear cover and a board are mounted. Because of this, there poses a problem that the shape of the control circuit board is subjected to restriction conditions.
In the aforementioned conventional techniques, a gear is constituted merely by a spur gear, and when a motor is installed or at the time of backlash, an excessively large load is applied to the gear, thus posing a problem that the gear is broken.
In the aforementioned conventional techniques, since a motor and a control circuit board are connected through a conductor, there poses a problem that when an excessive tensile stress is exerted between the motor and the control circuit board, the conductor is broken. Further, workability of the connection work was poor.
In the aforementioned conventional techniques, radiation of the control circuit board is not taken into consideration, thus posing a problem that heat generated in the control circuit board is not radiated from the control circuit board, and at high temperature, the control circuit is erroneously operated.
In the aforementioned conventional techniques, a circuit board receiving case (hereinafter called a board case) constituted from a housing and a cover is of a closed construction, thus posing a problem that when the board case is contracted or expanded, excessive stress is applied to the control circuit board or the board case, and the control circuit board or the board case is broken.
In the aforementioned conventional techniques, a positional relation between the rotational center axis of the magnet and the sensor is deviated, and a change in magnetic flux crossing the sensor is not a point symmetry, posing a problem that a sensor output is different every product.
In the aforementioned conventional techniques, there poses a problem that the sensor output is affected by the peripheral temperature of the sensor, and accordingly, the resolution is deteriorated due to the change in temperature.
In the aforementioned conventional techniques, there poses a problem that where an angle is measured over 360 degrees, since a first Hole element and a second Hole element are necessary in addition to an MR sensor, the sensor mechanism is complicated.
In the aforementioned conventional techniques, there poses a problem that in order to keep the distance between centers of the gears, a gear case (housing) and a board case (cover) are provided with counterbores, and the distance between the gears is varied due to the assembling tolerance or processing tolerance.